serial_mx31: allow it to work with mx27 too and rename to serial_mxc

UART hardware on i.MX27 is the same as on the i.MX31 so we just
need to provide the driver with correct address of the registers.

Signed-off-by: Ilya Yanok <yanok@emcraft.com>
diff --git a/include/configs/qong.h b/include/configs/qong.h
index 7e67185..64d0214 100644
--- a/include/configs/qong.h
+++ b/include/configs/qong.h
@@ -49,7 +49,7 @@
  * Hardware drivers
  */
 
-#define CONFIG_MX31_UART	1
+#define CONFIG_MXC_UART	1
 #define CONFIG_SYS_MX31_UART1	1
 
 /* FPGA */